Pyramidal diffuser



FIG. 1 is a top and left front perspective view of a pyramidal diffuser, showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front side elevational view thereof, the left and right side views thereof being mirror images of the front view shown; and,

FIG. 4 is a bottom plan view thereof.

The broken lines adjacent to the surfaces containing shading, which show the boundary of the claimed design, and all other portions of the design shown in broken lines shown in the figures form no part of the claimed design. 

The ornamental design for a pyramidal diffuser, as shown and described. 